Generally, there has been an increasing need for effective separation, alignment, and manipulations of colloidal and cellular suspensions or droplets and other particles based on the increasing number of systems utilizing microscale transport properties. These types of systems have significant parallelization and high throughput. Examples of applications for these systems include genetic analysis, molecular separations, sensors, imaging, printing, and surface patterning.
In one example, manipulation and positioning of the colloidal and cellular suspensions or droplets, and other particles is useful if imaging of the particles is desired. For example, the use of fluorescence detection is a ubiquitous practice in microbiology and biochemistry as well as colloidal science, biophysics and several other disciplines. Labeling cells, cellular components or individual biomolecules, or particles with molecular or colloidal fluorescent probes has enabled the visualization of several cellular metabolic and bio-molecular assembly processes. As such, methods involving fluorescent tagging, excitation, and detection may rely on methods of aligning, sorting, and manipulations.
An example of a known separation system is a fluorescence activated cell sorting (FACS) system that sorts and manipulates cells in continuous microfluidic flows. Fluorescence labeling of cells combined with traditional macroscopic FACS systems allow for the identification and separation of rare cells from concentrated suspensions, the sequestration of cells displaying desired physiological properties or metabolic states, and the parsing of large combinatorial libraries for specific information. A FACS system, however, can be complex and cumbersome. Furthermore, FACS, as well as other known alignment and sorting methods, may be improved by simplifying signal acquisition and interpretation to allow for closer to real-time feedback.